Through tubing cementing plug apparatus

ABSTRACT

THE METHOD OF CEMENTING A POROUS SUBSURFACE EARTH FORMATION IN WHICH WELL CASING IS SET AND PERFORATED, WHEREIN A BODY OF CEMENT SLURRY IS DISPLACED THROUGH THE TUBING, AND A BRIDGE PLUG IS EMPLOYED TO CLOSE OFF THE LOWER END OF THE TUBING, FOLLOWING DISPLACEMENT OF THE CEMENT SLURRY THROUGH THE PERFORATIONS. A BRIDGE PLUG FOR USE IN PERFORMING SUCH A METHOD, SUCH BRIDGE PLUG HAVING ANCHOR SLIPS RELEASABLY EXPANDABLE INTO ENGAGEMENT WITH THE TUBING WHEN AN EXPANSIBLE SPRING DEVICE AT THE LOWER END OF THE PLUG EMERGES FROM THE LOWER END OF THE TUBING.

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United States Patent O 3,572,433 THROUGH TUBING CEMENTING PLUG APPARATUSMartin B. Conrad, Carpinteria, Calif., assignor to Baker Oil Tools,Inc., City of Commerce, Calif. Filed May 8, 1969, Ser. No. 823,030 Int.Cl. E21b 33/129, 33/16 U.S. Cl. 166-132 16 Claims ABSTRACT OF THEDISCLOSURE The method of cementing a porous subsurface earth formationin which well casing is set and perforated, wherein a body of cementslurry is displaced through the tubing, and a bridge plug is employed toclose oif the lower end of the tubing, following displacement of thecement slurry through the perforations. A bridge plug for use inperforming such a method, such bridge plug having anchor slipsreleasably expandable into engagement with the tubing when an expansiblespring device at the lower end of the plug emerges from the lower end ofthe tubing.

In the completion or treatment of certain oil and gas wells, it may benecessary or desirable to displace a pumpable cement slurry into aporous formation in which casing has been set and perforated. However,if well tubing is disposed in the well casing, the displacement of thecement downwardly through the well tubing and thence into the largercasing poses problems which are difficult to solve. One of theseproblems would be the provision of a cementing plug capable of beingdisplaced downwardly through the small diameter tubing and also beingcapable of outward expansion into engagement with the larger diametercasing, so that a following fluid, which is normally employed todisplace the cement slurry, will not bypass the cement slurry and itselfbe displaced into the formation being cemented, on the one hand, andwhich, on the other hand, will prevent the return flow of the cementfrom the formation.

The present invention provides a method for cementing wells of theaforementioned type where the cement slurry is to be displaced throughtubing and thence into a larger diameter casing which has beenperforated to establish communication between the casing and a porousformation.

More specifically, the invention provides a method whereby a body ofcement slurry is introduced into the well tubing and is displaceddownwardly through the tub- `ing by a following fluid, wherein a plugdevice is pumped downwardly through the tubing in the following iluid ata distance above the cement slurry, calculated to effect displacement ofthe cement through the casing perforations and into the porousformation, or to iill the casing to a predetermined point below thetubing, the plug being anchored at the lower extremity of the tubingfollowing displacement of the cement to prevent further fluiddisplacement and to prevent return ow of the cement from the formationinto the casing. The cement may then be allowed to set up in theformation, after which the plug is removed from the tubing. Thereafter,various through tubing operations may be performed, such as, forexample, the perforation of a higher subsurface zone traversed by thecasing. In the practice of the present method, the usual through tubingplugs or dividers may be employed to separate the charge of cementslurry from fluid in advance of the cement slurry and the displacementuid following the charge of cement slurry.

In accomplishing the foregoing, the invention also provides a noveltubing plug apparatus adapted to provide a ice seal with the tubing andto be displaced downwardly through the tubing, the plug anchoring in thetubing following downward movement of a lower portion of the plugapparatus, such as a spring actuator, into the casing below the lowerextremity of the tubing. More particularly, the tubing plug has normallyretracted anchor slips adapted to be expanded laterally into anchoringengagement with the tubing, such slips being normally held in retractedposition by latch means which are releasable when the spring actuatoremerges from the lower end of the tubing. In order to release the slipsfrom the anchoring engagement with the tubing, the plug device isoperable by the imposition of a longitudinal force on the tool mandrelto relieve the wedging action on the anchor slips, and to by-pass andrelease the sealing means from the plug device as the latter is pulledor pushed from the well tubmg.

-T his invention possesses many other advantages and has other purposeswhich may be made more clearly apparent from a consideration of a formand method embodying the invention. This form and method are shown anddescribed in the present specification and in the drawings accompanyingand constituting a part thereof. They will now be described in detail,for the purpose of illustrating the general principles of the invention;but it is to be understood that such detailed description is not to betaken in a limiting sense.

Referring to the drawings:

FIGS. 1a, 1b, lc and 1d, respectively, illustrate operational steps incementing a zone in a cased well by pumping cementitious materialthrough tubing disposed in the well casing;

FIG. 2 is a Vertical section through a separation plug employed in thepractice of the method;

FIGS. 3a, 3b and 3c together constitute a vertical section through atubing plug embodying the invention, and being run through the tubing,FIGS. 3b and 3c being, respectively, downward continuations of FIG. 3a;

FIGS. 4a and 4b together constitute a vertical section illustrating thetubing plug anchored in the tubing following emergence of its springactuator from the lower end of the tubing, FIG. 4b being a downwardcontinuation of FIG. 4a;

FIGS. 5a, 5b and 5c together constitute a vertical section illustratingthe tubing plug being released from the tubing, FIGS. 5b and 5c,respectively, being a downward continuation of FIG. 5a; and

FIGS. 6a, 6b and 6c together constitute a vertical section illustratingthe tubing plug being pulled upwardly through the tubing followingrelease of the plug, FIGS. 6b and 6c, respectively, being downwardcontinuations of FIG. 6a.

As seen in FIGS. la, lb, 1c and 1d the present invention involves thetreatment or cementing of a well wherein a Well casing C has been set ina Well bore W which traverses a subsurface strata or zone Z1. The casinghas Ibeen perforated at P to provide communication between the casing Cand the zone Z1. Above the `zone Z1, the casing C also traverses asecond Zone Z2, but the casing has not been perforated at the Zone Z2.Extending downwardly from the top of the well from the casing C is atubing string T, at or near the lower end of which a conventional packerA is set and anchored against the casing to provide a seal between thetubing T and the casing C. If the formation or zone Z1 is, for example,a porous but non-productive formation, it may be necessary or desirableto displace cement slurry into the formation or `zone Z1 through theperforations P in order to block off or seal such formation. Thereafter,the casing C may be perforated at the productive formation or zone Z2.

The conduct of such cementing operation through the tubing string where,as in the present case, the formation Z1 is porous poses problems ofaccurate iluid and cement slurry measurement to appropriately block olfthe zone Z1. Various through tubing cementing operations have heretoforebeen employed, but such operations have not been altogethersatisfactory.

In accordance with the present method, the cementing of the formation orzone Z1 through the perforations P involves the utilization of a bridgeplug or tubing plug B adapted to form a seal within the tubing T and tomove with a stream of following fluid employed to displace the cementthrough the perforations P, the cement being, in the specificallyillustrated embodiment, preceded by a separation plug or fluid divider,generally denoted at D. The body of cement slurry is indicated at E.Also, in the illustrated employment, the body of cement slurry E isseparated from the following uid in the fluid column by an upperseparator or divider plug F which may correspond to the plug D.

The details of the separation plugs or dividers D and F will be bestunderstood upon reference to FIG. 2, while the details of the tubingplug B will best be understood upon reference to FIGS. 3a through 6c.

The known type of plug or fluid divider illustrated in FIG. 2 is usedfor the leading separation plug D and also for the following plug F.More particularly, the separation plug comprises an elongated mandrelcomposed of threadedly interconnected sections adapted to supportthereon an upper, upwardly facing tubing cup 11 and a lower, upwardlyfacing tubing cup 12, each of which is adapted for sliding and sealingengagement with the inside wall of the tubing string T. Between thetubing cups 11 and 12 and suitably attached to the mandrel 10 is alower, upwardly facing casing cup 13 foldable in the tubing string T andof sucient diameter as to expand outwardly into engagement with theinside wall of the casing C upon the emergence of the cup 13 from thetubing T. Above the casing cup 13, but below the tubing cup 11, is anupper, upwardly facing casing cup 14 foldable in the tubing T and whichis also of suicient dia-meter as to expand outwardly into sealingcontact with the casing C upon its emergence from the tubing T. Thecasing cups 13 and 14 are relatively flexible, constituting simplydividers for separating the fluent material thereabove from thefluid-like material therebelow in the tubing T and in the casing C.However, the cups 13 and 14 are not required to withstand anysubstantial differential fluid pressure as they move downwardly with thecombined fluid column.

As will be hereinafter more fully described, the tubing plug B includesan elongate body on which are upper and lower tubing cups 21, 22 adaptedfor sliding engagement within the wall of the tubing T. On the body 20of the tubing plug B is an actuator assembly 23, including bow springswhich are held in deformed condition, as seen in FIG. lc, when the plugB is within the tubing T, but which expand, as seen in FIG. 1d, whenthey emerge from the lower end of tubing T. The actuator means 23 isadapted to eifect the anchoring of releasable anchor means 24 againstthe wall of the tubing T following emergency of the actuator means 23from the lower end of the tubing T. Following completion of thecementing operation, the tubing plug B is removed from the tubing T.

With the foregoing general description in mind, the practice of thepresent method will now be described. As seen in FIG. 1a and asindicated by the arrows, a column of fluid in the tubing T and in thecasing C may flow downwardly and through the casing perforations P intothe zone Z1. In order to assure that the tubing T has no restrictions,offering impediment to the completion of the operation, a drift plug 25having a cup 26 slidably engageable within the tubing T may be displaceddownwardly through the tubing T and into the 4 casing C, therebyassuring a minimum diameter opening downwardly through the tubing T.

Thereafter, at the top of the well, the separator or divider plug D isintroduced into the uid column in the tubing T followed by the body ofcement slurry E. Above the cement slurry E, the upper separation plug Fis introduced into the tubing T, followed by displacement fluid, whichis pumped downwardly through the tubing T to effect the downwarddisplacement of the body of cement slurry E and the plugs D and F, theplugs D and F effectively isolating the cement slurry from the fluid inadvance thereof and the displacement fluid thereabove, as seen in FIG.lb.

A suitable interval above the upper separation plug F, the tubing plug Bis introduced into the tubing T, to be pumped downwardly therein withthe displacement fluid. As the lower separation plug D emerges from thelower end of the tubing T, the plug cups 13 and 14 expand outwardly intosliding engagement with the larger diameter casing C, as seen in FIG.lc. The plug D thereafter functions as a divider between the uid inadvance of the cement slurry E and the cement slurry itself. As seen inFIG. ld, the upper divider plug F then emerges from the lower end of thetubing T and its cups 13 and 14 extend into sliding engagement with thecasing C, so that the plug F acts as a divider between the following uidabove the plug F and the body of cement slurry E as the column of fluidcontinues to move downwardly through the well casing C.

Such further downward movement of the column of fluid in the well causesthe lower separator plug D- to reach a point at which at least the lowercup -13 is below the lo'wermost perforations P, at which time furtherdownward movement of the bottom separator plug Dy is arrested, due tothe presence of a static column of uid in the casing C below theperforations P. However, the cement slurry E will continue to bedisplaced downwardly past the upper casing cup 14 of the separation plugD, and outwardly through the perforations P, by the following fluidabove the separation plug F. Such displacement of the cement slurry Ewill continue until the tubing plug B reaches the lower end of thetubing string T; whereupon the actuator means 23 of the tubing plug Bemerges from the lower end of the tubing T and effects anchoring of theanchor means 24 against the tubing, arresting further downward movementof the tubing plug B.

Anchoring of the tubing plug B will be indicated by a substantialincrease in pressure at the top of the `well, whereupon pumping of thefollowing iluid ceases, the tubing T being shut-in at the surface tohold the cement slurry 'E in the formation Z1 or in the casing immobileuntil the cement has had an opportunity to set. Thereafter, as will bemore fully explained hereinafter, the tubing plug B may be removed fromthe tubing T. After removal of the tubing plug B, the casingI C at theupper subsurface Zone ZZ may be perforated, if desired, by the usualthrough tubing perforating equipment.

Referring. now to FIGS. 3a through 6c, the structure of the tubing plugB will be more fully described.

The tubing plug B comprises an elongate, sectional, tubular bodycomprising an upper body section 30 which is threadedly connected, as at31, in a threaded bore of an intermediate body section 32. Disposed uponthe body 30 is an upwardly facing sealing means or packing cup 33sealingly engaged against an annular seat 34 provided on the bodysection 30 and by an upwardly and outwardly extended flange 35 at theupper extremity of the intermediate body section 32.

The intermediate body section 32 extends downwardly and has a threadedlower end 36 engaged in the threaded bore 37 of a lower body section 38.An expander cone 39 is disposed about the intermediate body section 32adjacent the lower end of the latter. In the running-in condition of theplug, as shown in FIGS. 3a through 3c, the expander cone `39 is confinedagainst axial movement relative to the body section 32 between anupwardly facing shoulder 40 provided at the upper extremity of the lowerbody section 38 and a number of outstanding tapered projections 41 onthe intermediate body section 32, these projections `41 being formed oncircumferentially spaced resilient body webs or arms 42 which areprovided by forming longitudinal slots 43 in circumferentially spacedrelation about the body section 32.

The webs 42, when the tool is in the running-in condition, are heldagainst inward flexure by a cylindrical end portion or head 44 of acenter rod 45 extending longitudinally within the body sections 32 and30 and projecting through a top cap 46 threadedly connected, as at 47,to the upper end of the upper body section 30. This rod 45 is releasablysecured within the upper body section 30 by a shearing ring 48 disposedin an annular groove 49 in the rod 45, and extending into acircumferential groove 51 delined between a shoulder 50 in the end cap46 and a split retainer ring 52 disposed in a counterbore l53 in theupper end of the body section 30.

A set of upper by-pass ports 54 extend radially in the tubular upperbody section 30 above the packing cup 33, a set of lower by-pass ports55 extending radially through the upper end of the intermediate bodysection 32. These ports 54 and 155 establish communication between theannulus 56 surrounding the body of the tubing plug and the bore 57extending longitudinally of the body of the plug B. In order to preventcommunication between the -bore 57 above the cup 33 and the bore belowthe cup 33, the rod 45 has a cylindrical section 56a provided with asuitable side seal 57a in the form of an O-ring sealingly engaged withinthe bore 57. Thus, lluid above the plug assembly B may be pumpeddownwardly through the tubing T and will act on the cup 33 to force theplug assembly correspondingly downwardly.

At its upper end, the rod 45 is threaded at 58 for engagement in thethreaded bore '59 of a typical well tool recovery head 60 having adownwardly facing shoulder 61 adapted to be engaged by a suitable wireline fishing tool (not shown) when it is desired to release the plug Band pull the same from the tubing T, as will hereinafter be described.

Cooperative with the expander 39 for the purpose of anchoring the plug Bin the tubing T, when released to do so, is the anchor means 24 whichincludes circumferentially spaced Iwedgelike slip elements 62 havingdownwardly facing teeth 63 adapted to bite into the tubing T when theslips 62 are expanded. These slip elements have resilient arms 64extending longitudinally of the lower body section 38, which areintegral 'with a slip supporting ring 65 extending about the lower body38. This ring 65 is initially retained against longitudinal movementwith respect to the body 38 to hold the slip elements 62 out of wedgedrelation to the expander 39 and in retracted position, as shown in FIG.3b. In order to retain the ring 65 against such movement, releasablelatch means including ball detents 66 are provided, these balls 66 beingdisposed in radial holes 67 in the lower body 38 and engaged in anannular generally V-shaped groove 68 in the ring 65. A longitudinallyshiftable latch rod 69 is disposed within the bore 70 of the lower bodysection 38, the rod 69 having adjacent its upper end a cylindricalenlargement or head 71 positioned within or behind the balls 66 to holdthe latter outwardly in the groove 68. Between the slip elements 62 andthe ring 65, the body section 38 is provided with an external ring 72providing a downwardly facing shoulder 73 in opposed spaced relation tothe ring 65, this shoulder 73 being cooperative with the ring 65 in amanner hereinfater to be described.

Spring means including a helical compression spring 74 is provided tonormally bias the slip 65 upwardly when the ball detents 66 arereleased. Thus, the upper end of the spring 74 abuts the slip ring 65,its lower end abutting an annular spring seat collar 75 aflixed to thelower body 328 by suitable screw fasteners 76.

The actuator means 23 are provided for holding the cylindrical retainingportion 71 of the rod 69 in engagement with the ball detents 66, suchmeans being operative to shift the rod 69 upwardly to remove thecylindrical portion 71 from the ball 66 when the plug B is to beanchored in the tubing T. This actuator means includes an upper or endmember 77 threadedly connected, as at 78, to the lower end of the lowerbody section 38. The member 77 has a cylindrical downward extension 79telescopically disposed about the upward cylindrical section 80 providedon a lower actuator member 81. These actuator members 77 and 81 areinterconnected by a number of circumferentially spaced outwardlyexpandable bow springs 82. The upper end 83 of each bow spring isprovided with a flange conned within an annular groove 84 in the member77 by a retainer collar 85 secured to the end member 77 by suitablescrew fasteners 86. The lower end 87 of each bow spring 82 is providedwith a ilange confined within a groove 88 in the lower actuator member81 by a retainer collar 89 secured to the member 81 by a suitable screwfastener 90. Normally, the boW springs 82 will expand outwardly, causingtelescopic contraction of the cylindrical extensions 79 and 80 of themembers 77 and 81. However, when the bow springs are conned within thetubing T, they are elongated to effect telescopic extension of thesections 79 and 80 of the actuator members 77 and 81 to the positionsshown in FIG. 3b.

Extending downwardly from the actuator member 81 is a tubular body 91,this body 91 carrying a lower upwardly facing packer cup 92 bearingagainst an annular seat 93 on the body 91 and against a lower packingsupport collar 94 which is provided with an upwardly and outwardlyextended end flange 95.

For purposes which will hereinafter appear, the packer support 94 isreleasably latched to the actuator body 91. Accordingly, the body 91 isprovided with a radial hole 96 in which a ball latch 97 is disposed. Theball 97 cooperates with a conical seat or recess 98 in the packersupport 94, to hold the support 94 against downward displacement fromthe lower end of the body 91. The rod 69 previously referred to, andwhich holds the first-described ball detents 66 against displacementfrom the groove `68 of the slip ring 65, also includes a cylindricalenlargement 99 adapted to engage the ball 97 of the second latch meansto hold the latter in the seat 98. This cylindrical enlargement 99 alsocarries a side seal 100 sealingly engaged within the bore 101 of theactuator body 91.

At the base of the bore 101 of the actuator body 91 is a seat 102against which the lower conical end 103 of the rod 69 is adapted toabut, to limit downward movement of the rod 69 within the lower bodysection 38 and the actuator body 91 to a position at which thecylindrical portions 71 and 99 of the rod 69 initially hold therespective ball detents 66 and 97 outwardly.

At its lower end, the actuator body 91 may be provided with a guidespear 104 threadedly attached thereto and having a conical guide surface105 at its lower end. In addition, the lower end of the body 91 may beprovided with ports 108 leading into the bore 101, to facilitaterelative upward movement of the rod 69 in the bore 101 when the latchball 97 is to be released.

A third latch means is provided in the tubing plug B which, ashereinafter will appear, is adapted to hold the rod 69 in upwardlydisplaced relation to the ball detents 66 and 97. This third latch meansis incorporated in the upper actuator member 77, and includes alaterally shiftable latch dog 109 disposed in a radial bore 110 in themember 77 and conned therein by the retainer collar 85. This latch dogis normally biased inwardly by a coil compression spring 111 whichengages the collar 85 and seats in a recess 112 in the outer end of thedog 109. The dog 109 engages an enlarged cylindrical section 113 on therod 69, as shown in FIG. 3b, this cylindrical portion 113 having a lowerdownwardly facing shoulder 114 beneath which the dog 109 is adapted toengage to hold the rod 69 in an upper position within the body 38, 79after the latch balls 66 have been released, and to enable the tool tobe released from the tubing T and pulled upwardly therethrough to thetop of the well bore.

Referring now more particularly to FIGS. 4a and 4b, the tubing plugassembly B is illustrated as anchored in the lower end of the tubingstring T, in response to emergence `of the bow springs 82 of theactuator members 23 from the lower end of the tubing T. In these views,it will be noted that the upper rod 45 has maintained its position withrespect to the upper body section 30 and the intermediate body 32.Accordingly, the seal ring 57a still prevents communication between theupper by-pass ports 54 and the lower by-pass ports 55, and the enlargedcylindrical portion 44 at the lower end of the rod 45 is centrallylocated within the flexible webs 42, thereby maintaining the expander orcone 39 against upward movement relative to the intermediate bodysection 32. However, when the bow springs 82 emerge from the lower endof the tubing T into the larger diameter of the casing C, these springsare free to expand laterally outwardly and contract lengthwise, movingthe actuator body 91 upwardly with respect to the lower body section 38,which moves the actuator rod 69 upwardly with it within the body section38. Such upward movement of the rod 69 elevates the enlarged cylindricalportion 71 above the latch balls 66, thereby releasing the latch meanswhich holds the slip ring 65 against upward movement and permitting thespring 74 to expand and shift the slip ring 65 and the slips 62 upwardlyalong the cone 39 and laterally outwardly into anchoring engagement withthe tubing T, thus preventing further downward movement of the plugassembly B. Such anchoring of the plug assembly B will be indicated atthe top of the well by an increase in the pressure of the followingfluid being pumped downwardly through the tubing string T, since thefluid cannot by-pass through the ports 54 and 55.

In addition, upward movement of the rod 69 within the body section 38,as shown in FIG. 4b, moves the downwardly facing shoulder 114 on thecylindrical enlargement 113 of the rod 69 above the latch dog 109, thelatter being shifted inwardly by the spring 111 under the shoulder 114to prevent return downward movement of the rod 69 to its initialposition.

The plug assembly B will remain anchored in the tubing T under thesecircumstances until the plug is positively released. While the plug Bremains anchored, the cement slurry, which has been displaced into theformation or zone Z1, will be held immobile to allow it to set up toplug olf that formation by maintaining pressure on the fluid in thetubing string T above the plug assembly B.

When it is desired to release and remove the plug assembly from thetubing T, such result can be effected by either pushing the plugdownwardly and out of the tubing, or by pulling it upwardly through thetubing to the top of the well bore. Release by pushing downwardly isillustrated in FIGS. 5a, 5b and 5c, release by pulling upwardly throughthe tubing being illustrated in FIGS. 6a, 6b and 6c.

As disclosed in FIGS. 5a to 5c, the tubing plug assembly B is releasedby applying a downward force to the recovery head 60 (not shown in FIG.5a) by a suitable jarring apparatus on a wire line (not shown), which istransmitted to the center rod 45 to shear the ring 48 and effectdownward movement of the rod 45. Such downward movement of the rodserves the purpose of moving the lower cylindrical portion 44 of the rod45 downwardly within the flexible webs 42 from its position behind thecone 39, so that the webs 42 are free to flex inwardly in response todownward movement of the upper body section and the intermediate bodysection 32. This downward movement is caused by engagement of theenlarged cylindrical portion 56a of the rod with the upwardly facingshoulder 56b in the body section 32, downward movement of the bodysection 32 causing the webs 42 to be cammed inwardly by the downwardlytapered lower surfaces 41a of the web projections 41. Following suchinward deflection of the web 42, the downward wedging action of theexpander 39 on the slips is relieved, so that the expander 39 is nolonger in condition to retain the slips 62 anchored against the wall ofthe tubing T. The downward movement of the body sections 30, 32, 38causes engagement of a ring 72 on the lower body section 38 with thering7 65 to urge the latter downwardly and free the slips from wedgingrelation to the expander 39.

The downward application of force on the rod 45 and body of the tool iscontinued until the entire plug is ejected downwardly from the tubing T,whereupon it will drop or gravitate to the top plug F. During thedownward movement of the plug and its ejection from the tubing T, theby-pass ports 54, are in communication, since the cylindrical portion56a and its seal ring 57a have been lowered below the ports 55, allowingfluid to by-pass around the upper packing cup 33.

As illustrated in FIGS. 6a, 6b and 6c, the tubing plug B can be releasedfrom its anchored position in the well casing and elevated through thetubing T to the top of the well. By use of a suitable retrieving tool(not shown) lowered in the tubing on a wire line (not shown), suchretrieving head engages the recovery head 60 and latches under itsdownwardly facing shoulder 61, in a known manner. An upward jar is takenon the wire line to jar upwardly on the rod 65, which shears the ring 48and moves the rod 45 upwardly within the body of the tool, until theenlargement 56a engages the split retainer ring 52, as disclosed in FIG.6a. With the rod in this condition, the ports 54 and 55 are incommunication with each other through the interior of the body section30 and 32, permitting uid to by-pass around the upper packing cup 33.Accordingly, upward movement of the wire line and rod 45 connectedthereto will raise the body sections and the entire tool, including theexpander 39, the latch 109 elevating the rod 69 with the spring 74yieldably urging the slips 62 in an upward direction. However, suchslips will merely ride along the wall of the tubing T, since thedownwardly tapering expander 39 is being elevated therefrom. Also,duringthe initial stage of the elevating movement, the rod 69 is alsobeing elevated, as well as the bowed springs 62. When the bowed springsmove upwardly into the casing, they are compressed, shifting theactuator body 91 downwardly with respect to the lowel body section 38and the rod 69, including its enlargement 99, the downward movement ofthe body 91 along the cylindrical enlargement `99 removing the detentball 97 from engagement therewith, permitting it to drop out of thesocket 98 in the plug support 94, and thereby freeing the lower packingcup 92 and its support 94 from the body 91. As upward movement of theplug continues, the packing cup 92 will tend to re-enter the tubing T,but the uid column in the tubing will act downwardly on the packing cup92 and shift the latter, together with its support 94, from the lowerend of the actuator body 91, the packing cup 92 and actuator body 91dropping down into the well casing. The remainder of the plug assembly Bis now free to be moved upwardly through the tubing string T to the topof the well by appropriately elevating the wire line, the slips 62merely sliding upwardly along the wall of the tubing string.

I claim:

1. In a tubing plug for cementing a well zone traversed by a well casingin which tubing is disposed: an elongate tubular body, said body havingpacking means thereon for sealing engagement with the tubing, normallyretracted slip elements on said body expansible ouwardly into anchoringengagement with the tubing, an expander on said body, means for biasingsaid slip elements and said expander relatively longitudinally to causesaid expander to expand said slip elements, latch means normally holdingsaid biasing means inactive, and actuator means operable in` response tomovement of said actuator means out of the lower end of said tubing forshifting said latch means to released position.

2. In a tubing plug as dened in claim 1, said latch means comprising amember shiftable longitudinally of said body by said biasing means andconnected to one of said expanders and said slip elements, detent meanscarried by said body and normally held in engagement with said member,and means shiftable by said actuator means upon movement of saidactuator means out of the lower end of said tubing to release saiddetent means.

3. In a tubing plug as dened in claim -1, said biasing means comprisingspring means, said latch means comprising a member shiftablelongitudinally of said body by said spring means and connected to one ofsaid expanders and said slip elements, said member having an internalchannel, one or more balls carried by said body and engageable in saidchannel, openings in said body in which said balls are disposed, saidactuator means comprising a rod movable in said body and having a largediameter portion for holding said one or more balls in said channel anda reduced diameter portion for releasing said balls from said channelupon longitudinal movement of said rod in said body by said actuatormeans as a result of movement of said actuator means out of said tubing.

4. In a .tubing plug for cementing a well zone traversed by a wellcasing in which tubing is disposed: an elongate tubular body, said bodyhaving packing means thereon lfor sealing engagement with the tubing,normally retracted slip elements on said body expansible outwardly intoanchoring engagement with the tubing, an expander on said body, meansfor biasing said slip elements and said expander relativelylongitudinally to cause said expander to expand said slip elements,latch means normally holding said biasing means inactive, and actuatormeans operable in response to movement out of the lower end of saidtubing for releasing said latch means, said actuator means including apair of relatively longitudinally movable members, bow springs connectedto said members and deectable inwardly by said tubing to hold saidmembers in a first position, said bow springs expanding upon emergencefrom the lower end of said tubing to move said members to a secondposition, and means for releasing said latch means upon movement of saidmembers to said second position.

5. In a tubing plug for cementing a well zone traversed by a well casingin which tubing is disposed: an elongate tubular ibody, said body havingpacking means thereon for sealing engagement with the tubing, normallyretracted slip elements on said body expansible outwardly into anchoringengagement with the tubing, an expander on said body, means for biasingsaid slip elements and said expander relatively longitudinally to causesaid expander to expand said slip elements, latch means normally holdingsaid biasing means inactive, and actuator means operable in response tomovement out of the lower end of said tubing for releasing said latchmeans, said packing means including an upper packing cup and a lowerpacking cup respectively spaced on said body above and below saidactuator means.

6. In a tubing plug as dened in claim 5, including second releasablelatch means removably holding said lower packing cup on said body, andmeans for releasing said second latch means upon re-entry of saidactuator means in said tubing.

7. In a tubing plug for cementing a well zone traversed by a well casingin which tubing is disposed: an elongate tubular body, said body havingpacking means thereon for sealing engagement with the tubing, normallyretracted slip elements on said body expansible outwardly into anchoringengagement with the tubing, an expander on said body, means for biasingsaid slip elements and said expander relatively longitudinally to causesaid expander to expand said slip elements, latch means normally holdingsaid biasing means inactive, and actuator means operable in response tomovement out of the lower end of said tubing for releasing said latchmeans, said packing means including a packing cup on said body belowsaid actuator means, second releasable latch means removably holdingsaid packing cup on said body, and means for releasing said second latchmeans upon re-entry of said actuator means in said tubing.

8. In a tubing plug for cementing a well zone traversed by a Well casingin which tubing is disposed: an elongate tubular body, said body havingpacking means thereon for sealing engagement with the tubing, normallyretracted slip elements on said body expansible outwardly into anchoringengagement with the tubing, an expander on said body, means for biasingsaid slip elements and said expander relatively longitudinally to causesaid expander to expand said slip elements, latch means normally holdingsaid biasing means inactive, and actuator means operable in response tomovement out of the lower end of said tubing for releasing said latchmeans, said biasing means comprising spring means, said packing meansincluding a packing cup on said body below said actuator means, saidlatch means including a member shiftable longitudinally of said body bysaid spring means and connected to one of said expanders and said slipelements, detent means carried by said body, a rod in said body having aportion normally holding said detent means in engagement with saidmember, second releasable latch means normally holding said packing oupon said body, said rod having a second portion normally holding saidsecond latch means engaged with said packing cup, and said actuatormeans including means for moving said rod to release said detent meansupon emergence of said actuator means from said tubing and for releasingsaid second latch means upon re-entry of said actuator means in saidtubing.

9. In a tubing plug for cementing a well zone traversed by a well casingin which tubing is disposed: an elongate tubular body, said body havingpacking means thereon for sealing engagement with the tubing, normallyretracted slip elements on `said body expansible outwardly intoanchoring engagement with the tubing, an expander on said body, meansfor biasing said slip elements and said expander relativelylongitudinally to cause said expander to expand said slip elements,latch means normally holding said biasing means inactive, and actuatormeans operable in response to movement out of the lower end of saidtubing for releasing said latch means, said biasing means comprisingspring means, said packing means including a packing cup on said bodybelow said actuator means, said latch means including a member shiftablelongitudinally of said body by said spring means and connected to one ofsaid expanders and said slip elements, detent means carried by saidbody, a rod in said body having 'a portion normally holding said detentmeans in engagement with said member, second releasable latch meansnormally holding said packing cup on said body, said rod having a secondportion normally holding said second latch means engaged, said actuatormeans including a pair of relatively longitudinally telescopic sectionsof s'aid body, bow springs connected to said body sections anddeformable in said tubing to move said body sections in directions awayfrom each other, said bow springs moving said body sections indirections toward each other, said rod being engaged by one of said bodysections and shifted longitudinally of the [other body section uponemergence of s'ald bow springs from said tubing, dog means forpreventlng return movement of said rod relative to said other bodysection upon re-entry of said bow springs in said tubing, said bowsprings moving said one body section relative to the other to releasesaid second latch means to release said packing cup from said body uponre-entry of said bow springs in said tubing.

10. In a tubing plug for cementing 'a Well zone traversed by a wellcasing in which tubing is disposed: an elongate tubular body, said bodyhaving packing means thereon for sealing engagement with the tubing,normally retracted slip elements on said body expansible outwardly intoanchoring engagement with the tubing, an expander on said body, meansfor biasing said slip elements and said expander relativelylongitudinally to cause said expander to expand said slip elements,latch means normally holding said biasing means inactive, and actuatormeans operable in response to movement out of the lower end of saidtubing for releasing said latch means, said expander comprising a membershiftable on said body, said body having a shoulder engaged with one endof said expander member, said body having a plurality of inwardlyflexible arms extending through said expander member, projections onsaid arms above said expander member, said shoulder and said projectionsinitially preventing movement of said body with respect to said expandermember, and said arms being inwardly llexible to allow longitudinalmovement of said expander member relative to said slip elements torelease said slip elements from said tubing.

11. A tubing plug comprising: an elongate tubular body having an upperpacking cup facing upwardly thereon, a lower packing cup facing upwardlythereon, an upper rod in said body and projecting upwardly therefrom,recovery head means on said rod above said body, releasable means forinitially preventing longitudinal movement of said rod in said body andreleasable to allow reciprocation of said rod in said body, an expandercarried by said body, slips carried by said body, resilient means forbiasing said slips into wedging engagement with said expander,releasable latch means for holding said slips out of engagement withsaid expander, and actuator means for releasing said releasable latchmeans, said actuator means including spring means and being operable torelease said latch means in response to emergence of said spring meansfrom the lower end of a tubing in which the plug is movable.

12. A tubing plug as defined in claim 1l, wherein said actuator meansincludes an actuator rod shiftably disposed in said body, said actuatorrod having means for releasing said latch means in response to movementof said body relative to said actuator rod, and means for effecting suchrelative movement upon emergence of said spring means fro-m the lowerend of the tubing.

13. A tubing plug as defined in claim 11, wherein said actuator meansincludes an actuator rod shiftably disposed in said body, said actuatorrod having means for releasing said latch means in response to movementof said body relative to said actuator rod, said body includingrelatively longitudinally movable members, said spring means comprisingbow springs connected to said body members and deformable by the tubingto extend said body members relatively to each other, said bow springscontracting said body members relative to each other upon emergence fromthe tubing, one of said body members being engaged with said actuatorrod to move the latter and release said latch means in response tocontraction of said body members relative to each other.

14. A tubing plug as defined in claim 11, wherein said actuator meansincludes an actuator rod shiftably disposed in said body, said actuatorrod having means for releasing said latch means in response to `movementof said body relative to said actuator rod, said body includingrelatively longitudinally movable members, said spring means comprisingbow springs connected to said body members and deforma-ble by the tubingto extend said body members relative to each other, said bow springscontracting said body members relative to each other upon emergence fromthe tubing, one of said body members being engaged with said actuatorrod to move the latter and release said latch means in response tocontraction of said body members relative to each other, and latch meansreleasable upon extensible movement of said body members relative toeach other for releasably retaining said lower packing cup on said body.

15. A tubing plug as defined in claim 11, wherein said releasable meanscomprises shearable means connecting said upper rod to said body.

16. A tubing plug as dened in claim 11, said body having by-pass portsabove and below said upper packing cup, said body having a borecommunicating with said ports, said upper rod having seal means forpreventing communication between said upper and lower by-pass portsuntil said releasable means is released.

References Cited UNITED STATES PATENTS 1,670,964 5/1923 Hay et a1.166-132 2,146,219 2/1939 Knox 166-132 2,547,461 4/1951 Hampton 166-1323,018,830 1/1962 Springer 166-137X 3,196,950 7/1965 Hasha 166-132 IAN A.CALVERT, Primary Examiner U.S. C1. X.R. 166-137, 155

